Currently, radio communication systems such as mobile phone systems and wireless LAN (Local Area Networks) are widely in use. In addition, active discussions on next generation radio communication technology have been continued in order to further increase the speed and capacity of radio communication. For example, the 3GPP (3rd Generation Partnership Project), which is an international standards organization, has proposed a communication standard called LTE (Long Term Evolution) which allows data communication using a frequency band up to 20 MHz. Further, a communication standard called LTE-A (Long Term Evolution-Advanced) which allows data communication using up to five 20-MHz carriers (that is, 100 MHz) has been proposed as a next generation communication standard after the LTE standard.
In LTE and LTE-A, a data transmission scheme called MBSFN (Multimedia Broadcast multicast service Single Frequency Network) has been examined. In a radio communication system providing MBSFN transmission, one or more MBSFN areas each including multiple base stations are formed. The multiple base stations belonging to the same MBSFN area concurrently transmit data with the same content using the same frequency and the same modulation scheme. Data transmitted using MBSFN is sometimes referred to as the MBMS (Multimedia Broadcast Multicast Service) data. A mobile station combines MBMS data signals transmitted from multiple base stations, and demodulates and decodes the combined signal, which leads to an improvement in reception quality of the MBMS data.
As for LTE, a proposed technique is directed to a base station operating multiple cells, which acquires capability information from a mobile station in the case where frequency bands for data transmission and reception are different for different mobile stations, and determines a target cell of the mobile station based on the capability information (see, for example, International Publication Pamphlet No. WO 2008/023613). As for MBSFN, a technique has been proposed in which a serving cell selected from among cells in an MBSFN area and allocating radio resources to a mobile station notifies the mobile station of a frequency at which MBMS services are provided (see, for example, Japanese Laid-open Patent Publication No. 2009-182944). Another proposed MBSFN technique is directed to a control apparatus called MCE (Multi-cell/multicast Coordination Entity) which collects, via base stations, reports on quality of MBMS services evaluated by mobile stations and allocates radio resources based on the collected reports (see, for example, Japanese Laid-open Patent Publication No. 2009-246526).
In a radio communication system where multiple base stations may transmit data with the same content at the same frequency, a communication controller such as an MCE may select a frequency band used for transmitting the data with the same content and instruct the base stations to use the frequency band. On the other hand, the base stations may employ different frequency bandwidths, such as 10 MHz, 15 MHz, and 20 MHz, for their radio communication. Further, the base stations may operate at different center frequencies with the various frequency bands.
As a result, what remains an issue is how the communication controller selects the above-described frequency band used for transmitting the data with the same content. Assume, for example, that the communication controller selects a frequency band of 15 MHz for the transmission while there is a base station using a frequency band of only 10 MHz in the radio communication system. In this case, due to lack of radio resources, the base station is not able to transmit data for up to 5 MHz of the data with the same content. This may result in a decrease in reception quality at a radio receiver with respect to the data with the same content transmitted from two or more base stations.